Formats of bispecific antibodies (BsAbs)

Many formats have been developed for BsAb generation as listed in the following table.

Format	Description	Example BsAb	Trademark	Company
tandem VHH	Tandem VHH fragment-based BsAb	N/A
tandem scFv	Tandem ScFv fragment-based BsAb	AMG330	BiTE™	Amgen
Dual-affinity re-targeting antibody	Tandem domain-exchanged Fv (can also be used to fuse with Fc domain to create whole Abs)	Flotetuzumab	DART™	Macrogenics
Diabody	dimer of single-chain Fv (scFv) fragment	vixtimotamab	ReSTORE™	Amphivena Therapeutics
(scFv)2-Fab	a Fab domain and two scFv domains bind	A-337	ITab™	Generon/EVIVE Biotech
Rat–mouse hybrid IgG	Full-size IgG-like half antibodies from two different species	Catumaxomab	Triomab™	Trion Pharma
Hetero heavy chain, Common light chain	Hetero heavy chain, Common light chain	Emicizumab	ART-Ig™	Genentech/ Chugai/Roche
Controlled Fab arm exchange	Recombin the parental half antibodies	JNJ-64007957	Duobody™	Genmab/ Janssen
Hetero H, forced HL IgG1	KIH technology for heterodimerization of 2 distinct H chains, replacing the native disulfide bond in one of the CH1-CL interfaces with an engineered disulfide bond to enhance the cognate of H and L paring	MEDI5752	DuetMab™	MedImmune/ AstraZeneca
cH IgG1	Identical heavy chains; 2 different light chains: one kappa (κ) and one lambda (λ)	NI-1701	κλ body™	Novimmune SA
Hetero H, CrossMab	KIH technology; domain crossover of immunoglobulin domains in the Fab region	Vanucizumab	CrossMab™	Roche
scFv-Fab IgG	Fab-Fc; ScFv-Fc	Vibecotamab; M802	Xmab™ (the engineered Fc to enhance the generation of heterodimeric Fc); YBODY™	Xencor/Amgen; YZYBio
VH1-VH2-CH1-Fc1(G1) x VL2-VL1-CL-Fc2(G1)	2 binding motif in one half antibody	SAR440234	CODV-Ig™	Sanofi
VL1-CL1-VH2-CH2-Fc x VH1-CH1 x VL2-CL2	2 binding motif in one half antibody	EMB-01	FIT-Ig™	EPIMAB BIOTHERAPEUTICS
VH-1-TCR Cα x VL-1-TCR Cβ; VH-2-CH-2-Fc x VL-2-CL-2	KIH technology; TCR Cα/Cβ is used to substitute the CH1 and CL domain in one arm		WuXibody™	WuXi Biologics
C-terminal linker of Fc	Link the other molecules at the C-terminal of Fc	APVO442	ADAPTIR-FLEX™	Aptevo Therapeutics
Fc antigen binding site	2 natural binding sites; 2 additional binding sites in the Fc loop	FS118	mAb²	F-star Therapeutics

Pipeline and MOA (mechanism of action) of bispecific antibodies (BsAbs)

Bridge of 2 cells (engagers)

By binding with 2 antigens from 2 different cells, the BsAbs can physically link them together, thus these kinds of BsAbs are named “engagers”. The redirecting of immune cells to tumor cells by the engagers makes the immune cell activated and then eliminate the target cells. The T cell engagers are the most popular BsAbs which account for nearly half of the clinical trials aimed evaluating the BsAbs. NK cell engagers are recently developed BsAbs for NK cell-dependent tumor cell elimination.

The engagers in research, clinical trials and market are listed below. Genemedi offers the high quality, premade benchmark BsAbs for researchers.

Targeting multiple receptors

Bridging receptors is an obligate mechanism in which the binding of BsAbs to 2 receptors causes the activation or inhibition of each receptor. The co-activation or inhibition synergistically enhanced the biological effect of single antibody.

ligand redundancy

In addition to bind to the receptors, targeting redundancy for cytokines or angiogenesis factors represents an area of interest for BsAbs.

Biparatopic bsAbs

Instead of targeting two different proteins, bsAbs may be designed to simultaneously bind to two non-overlapping epitopes on the same target. Biparatopic targeting builds on increasing binding strength through antigen crosslinking and aggregation, thereby mimicking effects observed for antibody mixtures and polyclonal antibodies. Biparatopic bsAbs are therefore essentially a combinatorial concept

Cofactor mimetics

BsAbs can also be designed as a scaffold or cofactor linking enzyme and substrate together. One of the applications is the BsAbs used as a substitution of a critical clotting factor in the treatment of hemophilia.

Piggyback approaches

Exploit the first binding specificity of a BsAb as a transport modality for the second specificity are named the “piggyback” approaches. To cross the blood-brain barrier, one binding arm of the BsAbs are designed to target the transferrin receptor (TfR). The human serum albumin (HSA) targeting domain are used to extent the half-life of BsAbs, especially to BsAbs without Fc, for example the tandem ScFvs or VHHs. In addition, the piggyback approaches are also been used in promoting the degradation of pathogens.

View the Knowledge base of Bispecific antibodies:

- Bispecific antibodies: formats, applications and products
- Introduction about bispecific antibodies (BsAbs)
- Formats of bispecific antibodies (BsAbs)
- Pipeline and MOA (mechanism of action)of bispecific antibodies (BsAbs)